Pressure equalizer for blowout preventers



which 19, 1940. w. E. KING El AL 2,194,254

PRESSURE EQUALIZER FOR BLOWOUT PREVENTERS Filed Jan. 14, 1929 6 WINVENTORS BY F34;

ATTORNEYS.

Patented Mar. 19.1940

' UNITED ,STATES PATENT OFFICE Walter E. King and James S. Abercrombie,Houston, Tex; said King assignor' to said Abcrcrombie ApplicationJanuary 14,1929, Serial No. 382,280

9 Claims.

Our invention relates to blowout preventers to be employed on wellcasings in deep well operations where gas under pressure is encountered,to prevent the danger of blowing out of the well and injury to theequipment.

Wherever gas pressure is encountered in .well drilling precautions mustbe taken when the well is being drilled in to prevent the gas fromescaping upwardly from the well and increasing in force until thecontents of the well are blown out and damage is caused to the drillingrig. The gas pressure may be some times kept from escaping by the forceof the heavy mud pumped intothe well during the drilling operation butprecautions must be taken even when the pumps are operating and blow outpreventers of different kinds have been devised for closing the spaceabout the drill stem and the casing to prevent the gas and liquid fromescaping.

m It is diflicult to close the valves or rams which engage about thedrill stem or tubing in well operations when the well has startedblowing.

The pressure of the gas in the well against the valve members is sogreat that high pressure is a necessary to close the valves.

It is an object of the invention to provide means to equalize the gas orfluid pressure on opposite sides of the valves so that they may beclosed readily when necessity arises. We contemplate so constructing theblowout preventer that the well pressures may be exerted equally onopposite sides of the valves or rams so that an operator may then veryreadily close the same with ease and dispatch.

It is an object to provide means whereby the blowout preventer may beclosed into pipe-engaging position even under heavy gas pressures in thewell.

In the drawing herewith a preferred embodio ment of the invention isdisclosed.

Fig. 1 is a central vertical section through the apparatus equipped withour invention showing the valves in open position.

Fig. 2 is a similar view but showing the valves 5 in closed position.

The present invention is shown as applied to the type of blowoutpreventer disclosed in the prior application for patent of James S.Abercrombie, Serial No. 28,415, filed May '7, 1928. It

60 is possible, of course, to apply the invention to other similar typesof apparatus.

The device is intended for attachment at the upper end of the casing anda flange or coupling member I is shown at the lower side of the appasaratus threaded at 2 for engagement with the casing or an extensionthereof. This flange is adapted to be secured to the lower flange 3 ofthe blowout preventer body I. The two are adapted to be secured togetherby means of bolts 5.

The said body 4 has a central passage 8 there- I through to accommodatethe drill stem 1'. This passage has valve members I on each side thereofarranged to close about the drill stem and seal off the passage 8between the drill stem and the body of the preventer. These valves 1 arecylinl0 drical in shape and adapted to be moved in cylinders 8 extendingradially away from the passage 6. The said valves or rams may have the.forward end formed with cylindrical recesses to engage the drill stem 1.Packing strips 9 on said 15 pistons serve to preserve a tight seal sothat the pressure fluid may not escape around the valves.

These valves are shown as being adapted to operate by fluid pressure. Apiston rod Ill is' connected with each valve, said rod extending gothrough stufl'lng boxes II and I2 and having a piston l3 at the outerend thereof. The said piston l3 works in a cylinder l4 secured in fluidtight relation with a coupling member l5 through which the piston rodextends. 25

The cylinders H are closed on their outer ends except for an inlet portl6 for steam or other fluid under pressure. Said ports are connectedwith the pipe I! for pressure fluid.

On the inner ends of the cylinders M are passo sages l8 leading into thebody of the connecting member [5 and forming ports for the entrance ofpressure fluid on the inner side of the piston. These ports connect withthe pipe l9 also leading to the source of fluid under pressure, notshown. 35 It will thus be seen that pressure fluid may be introduced oneither side of each of the pistons l3 so that the same may be moved toand from the pipe in the operation of the valve members H. The furtheroperation of these valves will be obvious without further description.The difflculty encountered with this type of tool is that the gas orother fluid under pressure from the well sometimes blows up through thepassage 6 with such force that the piston valves 1 can not be advancedreadily to close. the passage. We contemplate overcoming this diflicultyby forming a bypass from the passage 5 below the valve around to a pointbehind the same, in this way equalizing the pressure on both ends of thevalves. This is accomplished by means of a pipe 20 connecting with aport II in the wall of the body 4 and leading to a port 23 in the memberI 5 on the rearward side of the valve so that the pressure may enter thecylinder 8 on the rearward'side thereof. A 56 valve 24 in the conductingline enables the operator to open or close this passage asdeslred. Inordinary practice this valve will be closed during the usual drillingoperations to prevent the passage of mud or water into the cylinder 8behind the piston. When danger of blowout occurs, however, this valvewill be opened so that pressure of gas from the well may be exertedthrough said pipe to the outer end of the cylinder I behind the valve'so that the pressure thereon may be equalized on both ends.

When this device is operated the valves 1 will be in the position shownin Fig. 1, the valve 24 being closed. When formations are encountered inthe drilling of the well in which gas is present in appreciablequantities it will be possible to open the valve 24 and proceed with thedrilling. If the accumulation of gas increases so that a blowout isstarted, the valve 24 being open will allow the pressure of the gas inthe well to be equalized on both sides of the valve 1. The operator willthen turn on the steam through the pipes I! so that it may enter theports I 6 on the outer ends of the pistons l3 and thereby force thevalves into closed position quickly and with little difliculty.

It will be obvious that with the gas thus equalized in the body of thepreventer that the valves may be closed by other means than steampressure and with little diillculty on the part of the operator. We donot, therefore, wish to be confined to this particular embodiment of theinvention.

It has been found that by the use of this attachment that much higherpressures may be contended with and larger and stronger types of valvesmay be employed and operated than is possible without the use of thisexpedient. Wells may be safely brought in which otherwise it would beexceedingly diillcult or impossible to handle.

Having thus described our invention, what we claim as new is:

1. In a blowout preventer, a tubular body having a longitudinal passagetherethrough for a pipe, valves movable radially relative to saidpassage to close the same about said pipe, means to conduct fluid fromsaid casing to points behind said valves to equalize the fluid pressureat-both ends of said valves and additional fluid operated means to movesaid valves, said last named means being independent of said equalizingmeans.

' 2. A blowout preventer including in combination a housing, a passagethrough said housing, rams movable transversely of said passage, meansto move said rams including pressure-operated pistons. and additionalmeans to co-operate with said first means in moving said rams wherebythe fluid pressure in said passage may be admitted behind said rams.

3. A control head for well casings comprising a body portion having acentral bore substantially aligned with the bore of the well casing anda chamber independent of and extending laterally from said central bore,a closure element in said independent chamber adapted normally to bemoved into contact with a string of pipe located in said central bore bymeans independent of pressure existing in the well,.means to seal aboutsaid element and chamber, and means for con ducting pressure fluid fromthe well into the independent chamber at the rear end of said sealingelement to equalize the pressure therein with the pressure existing inth central bore at the front end of said sealing element.

4. A control head for well casings comprising a body portion having acentral bore substantially aligned with the bore of the well casing anda chamber independent of and extending laterally from said central bore,a sealing element in said independent chamber adapted normally to bemoved into contact with a string of pipe located in said central bore bymeans independent of pressure existingin the well, means on said elementto seal against said chamber, and a by-pass ali'ording passage for gascontained in the well casing from below the said sealing element to theouter end of the independent chamber in which the sealing element islocated.

5. A control head for. well casings comprising a body portion having acentral bore substantially aligned with the bore of the well casing anda plurality of chambers independent of and extending radially from saidcentral bore, sealing ele ments located respectively in said independentchambers adapted normally to be moved into contact with a string oftubing located in said central bore by means independent of pressureexisting in the well, and a by-pass extending from below said sealingelements to the outer end of each of the independent chambers in whichthe sealing elements are respectively located, to permit the flow of gascontained within the well casing to the outer ends of the respectivesealing elements.

6. A control head for well casings comprising a body portion having acentral bore substantially aligned with the bore of the well casing anda plurality of chambers independent of and extending radially from saidcentral bore, sealing elements located respectively in said independentchambers in opposed relation to each other adapted normally to be movedinto contact with each other and with a string of tubing located in saidcentral bore by means independent of pressure existing in the well, anda by-pass extending from below said sealing elements to the outer end ofeach of the independent chambers in which the sealing elements arerespectively located, to permit the flow of gas contained within thewell casing to the outer ends of the respective sealing elements.

7. A control head for well casings comprising a body portion having acentral bore substantially aligned with the bore of the well casing anda plurality of chambers independent of and extending radially from saidcentral bore, sealing elements located respectively in said independentchambers in opposed relation to each other adapted normally to be movedinto contact with each other and with a string of tubing located in saidcentral bore by means independent of pressure existing in the well, aby-pass extending from below said sealing elements to the outer end ofeach of the independent chambers in which the sealing elements arerespectively located, to permit the flow of gas contained within thewell casing to the outer ends of the respective sealing elements, andmeans for controlling the fiow of gas through said by-passes.

8. A control head for well casings comprising a body portion having acentral bore substantially aligned with the bore of the well casing anda plurality of chambers independent of and extending radially from saidcentral bore, a closure head at the outer end of each independentchamber, sealing elements located respectively in said independentchambers in opposed relation to each other adapted normally to be movedinto contact with each other and with a string of tubing located in saidcentral bore by means independent of pressure existing in the well, anda by-pass extending from below said sealing elements to the outer end ofeach of the independent chambers in which the sealing elements arerespectively located, to permit the flow of gas contained within thewell casing to the outer ends of the respective sealing elements, saidby-pass comprising a string 01 pipe tapped at its opposite ends intosaid body portion and the outer end of the chamber respectively.

9. A control head for well casings comprising a body portion having acentral bore substantially aligned with the bore of the well casing anda plurality of chambers independent of and extending radially from saidcentral bore, a closure head at the outer end of each independentchamber, sealing elements located respectively in said independentchambers in opposed relation to each other adapted normally to be movedinto contact with each other and with I a string of tubing located insaid central bore by means independent of pressure existing in the well,a by-pass extending from below said sealing elements to the outer end ofeach of the independent chambers in which the sealing elements arerespectively located, to permit the flow of gas contained within thewell casing to the outer ends of the respective sealing elements, saidby-pass comprising a string of pipe tapped at its opposite ends intosaid body portion and the outer end of the independent chamberrespectively, and a control valve in said by-pass between said bodyportion and said independent chamber.

WALTER E. KING.

JAMES B. ABERCROMBIE.

